Gluten Free Rhubarb Cake

I love a simple, no-fuss cake and this gluten-free rhubarb cake definitely falls in that category. A moist and tender gluten-free buttermilk cake topped with fresh rhubarb, coarse sugar, and sliced almonds. Serve it as is or top it with a generous dollop of whipped cream. This Austrian Gluten Free Rhubarb Cake makes the perfect breakfast cake or a little something-something to serve for "Kaffee & Kuchen" (Mid Afternoon Coffee Break).

Recipe Ingredients Notes

Gluten Free Flour: To test this Gluten Free Rhubarb Cake recipe I have used my own gluten-free flour blend and Bob's Red Mill 1-to-1. Both of these blends yielded a tender, moist crumb and provided an outstanding flavor. It's worth noting that while I haven't tried other brands of flour in this recipe, it doesn't necessarily mean that they won't work. The flour blends used to create this exceptional recipe do include xanthan gum.

Almond Flour: The almond flour gives this gluten-free buttermilk cake its beautiful structure and moist crumb. If you prefer to keep this recipe nut-free, please substitute the almond flour with the same amount of gluten-free flour. You can also substitute the almond flour with hazelnut flour or walnut flour.

Buttermilk: I have tested this recipe with buttermilk and “homemade buttermilk” (which is basically milk with apple cider vinegar or lemon juice). I prefer the creaminess and thickness of real buttermilk over the homemade version. If you do not have access to buttermilk, plain kefir is a great substitute.

Rhubarb: When selecting rhubarb for baking, it is best to choose stalks that are firm, crisp, and brightly colored. The stalks should be free of blemishes and have a glossy appearance. Rhubarb can be found in the produce aisle of your grocery store or your local farmers market. Or if you are lucky enough, it may even grow in your backyard.

How to choose Rhubarb for baking

For baking with rhubarb, select firm and crisp stalks with a bright color, which can vary from pale green to deep red based on the variety. Avoid wilted or discolored stalks. While the size doesn't matter, thicker stalks are preferred by some because they hold their shape better during cooking.

It's worth noting that "forced" rhubarb, which is grown indoors in the dark, tends to be sweeter and more tender than outdoor-grown rhubarb. If you can find forced rhubarb at your local market or grocery store, it can be a great choice for baking.

Ultimately, the best way to determine which rhubarb to choose for baking is to use your senses. Look for stalks that are firm and brightly colored. Give them a gentle squeeze to make sure they are not too soft. If you can, give them a taste to get a sense of their tartness and flavor.

Preparing Rhubarb for Gluten Free Rhubarb Cake

Preparing rhubarb for this gluten-free buttermilk cake is simple. First, wash the rhubarb stalks under cold water and dry them with a paper towel. Remove both ends and any leaves as they are toxic.

Slice the stalks into small pieces, about ½ inch to 1 inch in length. If you like you may also cut some smaller pieces and add them to the actual cake batter. I only use rhubarb to top the cake. Make sure though to macerate the smaller pieces in a separate bowl.

Add the sliced stalks to a small bowl and toss them with some granulated sugar and lemon juice. You can even add some lemon zest if you like. Let the mixture sit, stirring occasionally, until the sugar has dissolved and the rhubarb has released some of its juices. This can help to balance out the tartness of the rhubarb and create a more complex flavor in baked goods. Let the mixture sit while you prepare the cake batter. Drain off any excess liquid though before adding the rhubarb to your recipe and reserve it for later use if you like. It does make a delicious drizzle for the finished Rhubarb Cake

How to make a Gluten Free Rhubarb Cake Batter

I like to use a 9″ spring pan to make this cake. I understand spring form pans are not something everyone has on hand. You can also use a 9×9 rectangular pan or 9" round cake pan. Even a 9x13 pan works for this recipe but please be aware that the cake will be thinner and bake quicker.

Step 1: Preheat the oven to 350F. Lightly spray the spring form with nonstick cooking spray and line the bottom with parchment paper. Set aside.

Step 2: Combine the room temperature butter, powdered sugar, vanilla extract, and almond extract (if using) in the bowl of the stand mixer or large mixing bowl. Mix at medium speed for about 3 minutes until lighter in color and smooth. Make sure to stop the mixer halfway through and scrape the sides of the bowl with a flexible spatula.

Step 3: Add the room temperature eggs, one by one, allowing 30 seconds between each addition. The batter will look curdled but once you add the dry ingredients, it will come back together.

Step 4: Combine the gluten-free multi-purpose flour, almond flour, baking powder, and kosher salt. Add the dry ingredients to the wet ingredients and mix until fully combined. The batter will be stiff.

Step 5: Add the room-temperature buttermilk and mix until fully incorporated. Make sure to scrape down the sides and the bottom of the bowl to make sure everything is combined.

How to bake a Gluten Free Rhubarb Cake

The oven should be preheated at this point to 350F as well as the cake pan should be ready to use.

Step 1: Transfer the gluten-free rhubarb cake batter to the prepared spring form and with a small offset knife, spread it out evenly. If you also want to have small chunks of rhubarb in the cake, make sure to fold them into the cake batter before transferring them to the spring form. Don't forget to drain the syrup!

Step 2: Retrieve the bowl with the sliced rhubarb. Drain the syrup and arrange the pieces of rhubarb on top of the cake to your liking.

Step 3: Sprinkle the cake with a generous amount of coarse sugar and sliced almonds.

Step 4: Place the rhubarb coffee cake in the preheated oven and bake at 350F for 45-50 minutes. The top of the cake will be golden brown and a cake tester insert in the center of the cake comes out clean. Please be aware that this cake does not contain a lot of sugar so it may look pale while a toothpick does come out clean.

Step 5: Remove the gluten free buttermilk cake from the oven and place it on a cooling rack. Allow the cake to cool in the pan for 10 minutes before removing the ring of the springform pan. To do so, run a knife around the edges (right between the cake and the ring). Then open the latch of the spring form and remove it. You can either let the cake cool completely on a wire rack or dust it with powdered sugar and cut and serve it while still warm. 

Serving Ideas

While this gluten-free rhubarb cake is amazing on its own, I love serving it with a dusting of icing sugar and some whipped cream. Maybe even a drizzle of the reserved rhubarb syrup. Serve the cake still warm with a scoop of vanilla ice cream for a special treat.

Variations of Gluten Free Rhubarb Cake

The gluten free buttermilk cake used to make this rhubarb cake is a great "base recipe". If rhubarb is not your thing, replace the fruit with blueberries, raspberries, peaches, or even canned (and drained) mandarins. The options are endless.

You can also top it with some brown sugar streusel or almond streusel before baking.

Storage & Freezing

To store leftover gluten-free rhubarb cake, keep it in an airtight container at room temperature if it will be consumed the same day. For longer storage, store it in the refrigerator in an airtight container. This cake will improve with time, but it should be eaten within 2-3 since gluten-free cakes with fresh fruit spoil easily. Allow it to come to room temperature before serving. The almonds on top of the cake may get soft over time since they absorb the liquid from the rhubarb.

To freeze the gluten-free buttermilk, make sure it is completely cool. Wrap the entire uncut cake in plastic wrap and place it in an airtight container or large ziplock bag. You can also freeze individual pieces this way. To thaw, transfer the cake from the freezer to the fridge and allow it to thaw overnight.

Note about Salt in my Recipes

I use Diamond Kosher Crystal Salt in all of my recipes unless otherwise stated. If use use a different brand or kind of salt in your kitchen please adjust accordingly since some salts can be saltier. If you use Morton’s Kosher Salt please be aware that their salt granules are smaller in size, denser, and crunchier and twice as salty.

Baking in grams

I share my recipes in grams and by weight since baking by weight is the most accurate way to bake. Digital Scales are very affordable and easy to use. You can purchase them on Amazon for less than a set of measuring cups. For small amounts under 10 grams, I like to use this Precision Pocket Scale. Measuring cups are very inaccurate which can cause significant errors when it comes to gluten-free baking or baking in general. Especially since I bake with gluten-free flours which weigh differently than “regular” flours. I do provide some ingredients like spices and leavening agents in measuring spoons. To learn more about Baking with a digital scale, make sure to check out my post about Baking by weight.

Note about Ovens and Oven Temperatures

All my recipes are tested and developed with a conventional oven. I always bake my baked goods on the rack placed in the MIDDLE of my oven. This way the heat coming from the bottom will not burn my baked goods.

If you are baking with convection (fan-forced), please adjust the recipes accordingly. Convection oven can cause baked goods to dry out quickly and still be raw inside. Since takes at least 15-20 minutes for a standard American Oven to be fully preheated. I highly recommend investing in an Oven Thermometer.

Substitutions and Modifications

Any dietary or ingredient modifications/substitutions to this recipe may alter the end result in appearance and taste. I test my recipes several times as published in this post and The Gluten Free Austrian Blog is not responsible for the outcome of any recipe you find on our website.